Systa it's not the world's largest spider , it's the world's largest spider web

Darwin's bark spider (Caerostris darwini) is an orb-weaver spider that produces one of the largest known orb webs, with anchor lines spanning up to 25 metres. The spider was discovered in Madagascar in the Andasibe-Mantadia National Park.The species was named in honour of the naturalist Charles Darwin, with the description being prepared precisely 150 years after the publication of The Origin Of The Species, on 24 November 2009.

Its silk is the toughest biological material ever studied ever studied, over ten times stronger than a similarly-sized piece of Kevlar. The average toughness of the fibres is 350 MJ/m3, and some are are up to 520 MJ/m3 making the silk twice as strong as any other spider silk known.
The web of Darwin's bark spider is remarkable in that it has not only the longest spanning web ever observed, but is among the largest orb webs ever seen, at an area of up to 2.8 m2. Nephila komaci, discovered in 2009, and some other Nephila species also make webs that can exceed one metre across.

According to professor Ingi Agnarsson, director of the Museum of Zoology at the University of Puerto Rico, the spider's web occupies a unique biological niche, stating: "They build their web with the orb suspended directly above a river or the water body of a lake, a habitat that no other spider can use". This position allows the spiders to catch prey flying over the water, with webs observed to have contained up to 32 mayflies at a time. The strong silk and large web are thought to have coevolved at the same time, as the spider adapted to the habitat.

Scientists are currently researching how the spider is able to weave such a large web over water along with being able to anchor drag lines on either side of a river.
Like other spiders of the genus, Darwin's bark spider displays extreme sexual dimorphism, with the large females and small males.